[MARMAM] New publication on the correlated loss of olfactory anatomy with deeper dive depth and longer dive duration in aquatic arctoid carnivorans

Deborah Bird dbirdseed at gmail.com
Thu Jul 16 09:56:52 PDT 2020


My co-authors and I are pleased to announce the publication of our new
paper in Ecology and Evolution on the correlated loss of olfactory anatomy
with deeper, longer diving behavior in aquatic carnivorans.

Olfaction at depth: Cribriform plate size declines with dive depth and
duration in aquatic arctoid carnivorans
Deborah J. Bird, Iman Hamid, Lester Fox-Rosales, Blaire Van Valkenburgh

Ecology and Evolution. 2020;00:1–15;
https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.6343

Abstract

It is widely accepted that obligate aquatic mammals, specifically toothed
whales, rely relatively little on olfaction. There is less agreement about
the importance of smell among aquatic mammals with residual ties to land,
such as pinnipeds and sea otters. Field observations of marine carnivorans
stress their keen use of smell while on land or pack ice. Yet, one
dimension of olfactory ecology is often overlooked: while un- derwater,
aquatic carnivorans forage “noseblind,” diving with nares closed, removed
from airborne chemical cues. For this reason, we predicted marine
carnivorans would have reduced olfactory anatomy relative to closely
related terrestrial carnivorans. Moreover, because species that dive deeper
and longer forage farther removed from surface scent cues, we predicted
further reductions in their olfactory anatomy. To test these hypotheses, we
looked to the cribriform plate (CP), a perforated bone in the posterior
nasal chamber of mammals that serves as the only passageway for ol- factory
nerves crossing from the periphery to the olfactory bulb and thus covaries
in size with relative olfactory innervation. Using CT scans and digital
quantification, we compared CP morphology across Arctoidea, a clade at the
interface of terrestrial and aquatic ecologies. We found that aquatic
carnivoran species from two lineages that independently reinvaded marine
environments (Pinnipedia and Mustelidae), have significantly reduced
relative CP than terrestrial species. Furthermore, within these aquatic
lineages, diving depth and duration were strongly correlated with CP loss,
and the most extreme divers, elephant seals, displayed the greatest
reductions. These observations suggest that CP reduction in carnivorans is
an adaptive response to shifting selection pressures during secondary
invasion of marine environments, particularly to foraging at great depths.
Because the CP is fairly well preserved in the fossil record, using methods
presented here to quantify CP morphology in extinct species could further
clarify evolutionary patterns of olfactory loss across aquatic mammal
lineages that have independently committed to life in water.


The publication can be found at:
https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.6343

PDF requests can be sent to dbirdseed at gmail.com


Deborah Bird

Department of Ecology and Evolutionary Biology
UCLA
610 Charles E. Young Dr.
Los Angeles, CA 90095
Cell: 310-245-2003
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